In this issue of Veterinary Clinics of North America: Food Animal Practice, guest editors Drs. Robert J. Van Saun and William S. Swecker, Jr. bring their considerable expertise to the topic of Vitamins and Trace Minerals in Ruminants. Optimal nutrition with adequate trace mineral levels guarantees proper function and nutrition of the animal, but purity and effectiveness are important concerns. In this issue, top experts in the field review trace mineral function, requirements, and content of common feeds, as well as specific diet challenges for ruminants and cattle.